Kinetic memory electrodes, catheters and cannulae

ABSTRACT

A conductive electrode-catheter, biological catheter cannula or the like which is easily inserted into the body and which is effectively anchored into a desired organ or tissue or properly located within a target cavity. The electrode, catheter, or the like incorporates a material, such as a known titanium-nickel alloy, having heat-activated mechanical memory. The device is formed and annealed at high temperature into a shape for effective anchoring or proper location in an organ or other structure of the body. Then at a temperature below its transitional temperature it is reformed into a shape for ease of insertion, and when located in the desired organ or structure is heated above its transitional temperature, thereby returning to its original annealed anchoring or proper locating shape.

United States Patent 1 1 Wilson 1 1 KINETIC MEMORY ELECTRODES,

CATHETERS AND CANNULAE I76] Inventor: Bruce C. Wilson, 34 Twickwood Ln., Glens Falls, NY. 12801 122 Filed: Mar. 1,1974

21 Appl.No.:447.340

[52] US. Cl l28/4l8; 128/206 E; 128/D1G. 4; 128/348; 128/350 R; 128/404; 128/418;

15l| Int. Cl. A6lb 5/02; A6lm 25/00 [58] Field of Search... 128/418, 419 P, 404. 2.05 R. 128/206 E 2.1 E, 348, 349 R, 350 R, 351,

DIG. 4; 3/1.7; 75/170. 175.5

I 56] References Cited UNITED STATES PATENTS 3.348.548 10/1967 Chardack 128/419 P 3.419.010 12/1968 Williamson 128/350 R 3.485.234 12/1969 Stevens 128/348 3.558.369 1/1971 Wang ct a1 75/1755 3.605.726 9/1971 Williams 128/205 F 3.606.592 9/1971 Mudurski ct a1 3/1.7 3 612 038 10/1971 Halligan 128/205 R 1 1 June 24, 1975 Harrnjanz 128/419 P Berkovits 128/419 P 57 ABSTRACT A conductive electrode-catheter. biological catheter cannula or the like which is easily inserted into the body and which is efiectively anchored into a desired organ or tissue or properly located within a target cavity. The electrode, catheter. or the like incorporates a material. such as a known titanium-nickel alloy. having heat-activated mechanical memory. The device is formed and annealed at high temperature into a shape for effective anchoring or proper location in an organ or other structure of the body. Then at a temperature below its transitional temperature it is reformed into a shape for ease of insertion, and when located in the desired organ or structure is heated above its transitional temperature, thereby returning to its original annealed anchoring or proper locating shape.

l5 Claims, 9 Drawing Figures PATENTEDJUN 24 I915 I F' 34. zza" KINETIC MEMORY ELECTRODES. CATHETERS ANI) CANNULAE BACKGROUND OF THE INVENTION This invention relates to conductive electrodecatheters. biological catheters. cannulae and the like. These devices are usually passed into and through a body orifice. incision. peripheral artery. vein. urogential or respiratory passage. etc.. of an animal or human body and advanced until they reach a desired organ. structure. or cavity within the body. It has a long been a problem to provide such an electrode. cannula. or catheter that is readily insertable into the body and easily advanced. while also being effectively anchorablc into a desired organ or properly locatable within a tar get cavity. Effective anchoring is desirable in the case of a cardiac electrode to insure positive electrode contact with the endocardium (inner wall of the heart) whether a pacemaker an EKG recorder. or the like is connected to the electrode. In the case ofthe biological catheter or cannula. proper location and anchoring is desirable whether the catheter is used for drainage, pressure recording. gas administration. or for injection of medication. dye. etc.. into the cardiovascular. urogenital. respiratory. lymph. or digestive systems. or into other body parts.

Various attempts have been made in the past to provide electrodes or catheters which are readily insert able while being effectively anchorable or properly locatable. US. Pat. Nos. 3.516.4l2. 3.348.548. and 3.729.008 show cardiac electrodes that are mechanically held straight during insertion. and then are allowed to flex into another shape. while US. Pat. No. 3.4l9.()l() shows a catheter that is mechanically held straight and then allowed to curve to properly locate it in a cavity to provide drainage. While the prior art devices have been generally acceptable. they have been cumbersome to operate and do not allow for a wide variety ofdesign modifications depending upon particular application.

SUMMARY OF THE INVENTION The present invention provides an electrode. catheter. or the like which is readily inscrtable while being effectively anchorable or properly local-ablev These properties are provided by forming the device of the present imention. either wholly or in part. of a material exhibiting mechanical memory that is triggered by heat. Examples of such a material are the titanium nickel alloy disclosed in US. Pat. Nos. 3.I74.85I and 3.672.879. and the titanium-nickel-cobalt alloy disclosed in U.S. Pat. No. 3.558.369. This first-mentioned alloy consists essentially of from 52-56% nickel by weight and correspondingly from about 429447: titanium by weight. said alloy having the structure ofa sub stantially TiNi phase from about 500C. to about 75/:(. This material is originally formed with restraint and by heat annealing (typically 95()-I.I(IUF.) into the shape desired once it is inserted into the body (such as a curve. angle. or any other of an infinite variety of single or multiple configurations]. Then the material is deformed at a temperature (typically room temperature] below its transitional temperature (from 32-33lF depending upon relative composition. but typically from 9Kl25F) into a shape facilitating easy insertion into the body (such as a straight rod). and the material is incorporated into the electrode. catheter. or

the like. After the electrode. etc.. is inserted into the body and advanced into the target place. the material is heated to its transitional temperature thereby returning the material to its original shape.

The titanium-nickel-cobalt alloy disclosed in US. Pat. No. 3.558.369 has the formula TiNi -Co wherein Ti denotes titanium and constitutes approximately 5() atomic 7r ofthe composition. and the term Ni ,(o denotes nickel and cobalt respectively and make up the remaining approximately 50 atomic percent of the composition. .v is a factor which varies from greater than (I to less than I whereby the relative percentage of nickel and cobalt varies inversely from less than I00 percent to more than 0 percent. The transitional temperature of this alloy can be varied depending upon relative composition from 396 to +33 lF. Otherwise. it is essentially the same as the abovementioned titaniumnickel alloy.

Once heated to its transitional temperature. the device will thereafter maintain its original shape even when cooled below its transistional temperature. The electrode. catheter. or the like of the present invention is thus easy to operate. and can be readily designed to fit a wide variety of applications.

OBJECTS OF THE INVENTION It is an object of the present invention to provide an improved electrode. catheter. cannula. or the like.

It is another object ofthis invention to provide an improved electrode. catheter. or the like that is readily insertable yet on command effectively anchorable or properly locatable.

It is a further object of this invention to fit an electrode. catheter. or the like with a transitional temperature activated mechanical memory material.

Other objects and advantages of the present invention will become clear from the ensuing detailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. Ia and lb are side elevational views partly in section of the tip and part of the shaft portions of a catheter according to the present invention shown in its transition and reformed shapes respectively while FIG. [1* is a side view of the tip and part of the shaft of a modification ofthe catheter shown in FIGS. la and II);

FIGS. 2a and 2b are side views of a ventricular pacing electrode according to the present invention showing in phantom the location of the transitional temperature activated mechanical memory material in the shaft in both the transition and reformed shapes;

FIGS. 31: and 3b are side views of an atrialventricular pacing electrode according to the present invention showing in phantom the location of transitional temperature activated mechanical memory material in both the shaft and tip portions in both the transition and reformed shapes;

FIGS. 4a and 4b are cross-sectional views taken along lines 4-4 of FIG. 2a showing alternative embodiments ofthe location ofthe transitional temperature activated mechanical memory material within the body of the electrode.

DETAILED DESCRIPTION OF THE INVENTION A catheter formed according to the teachings of the present invention. shown generally at It) and having a shaft portion II and a tip portion I2. is disclosed in FIGS. Ia and 1h. The catheter has a tubular body 13. preferably formed of plastic. silastic. rubber. or similar material. and a lumen 14. Fluid contained in lutnen I4 can be injected through holes I5 into a body part. or fluid can be drained from a body cavity or structure through holes and lumen 14. Liquid coupled pres sure recordings can also be made by attaching transducers or similar diagnostic equipment to lluid filled lumen 14.

A rod 16 of transitional temperature activated mechanical memory material is incorporated into the tip portion of the catheter. The rod l6 can either be di rectly incorporated into a portion of the body 13. or it can be affixed thereto. FIG. la shows the rod in a typical shape for properly locating the catheter within a particular body part. The rod is originally annealed into this shape before incorporation into the catheter. and then assumes this shape again after cooling and subse quent heating to its transitional temperature (typically 98-l 25F]. FIG. II) shows the rod in a shape for easy insertion and advancement into the desired body eavity. This is the reformed shape of the rod.

In operation. the rod 16 is formed into its properly locating shape-such as shown in FIG. luand is cooled down below its transitional temperature. The composition of the rod is preferably selected so that this transitional temperature is 98- l 25F. and the rod is cooled down to room temperature. Then the rod is reformed into a shape for ease of insertion into the body such as shown in FIG. lb-and is incorporated into the catheter body 13. Then the catheter is inserted into the body and advanced to the desired location. whereupon the rod 16 is heated above its transitional temperature. The heating can be done by any suitable means, one form of applying heat being the body heat itself. Where body heat is relied upon, it is obvious that the composition of the transitional temperature activated mechanical memory material must be selected so that it has a transitional temperature at or just below body temperature. Heating causes the rod 16 to assume its original shape- FIGS. la thereby properly locating the catheter 10.

FIGS. 2-4 show electrodes formed according to the teachings ofthe present invention. In FIG. 2a a ventricular pacing electrode shown generally at 20 is disclosed. The electrode has a shaft portion 21 and a tip portion 22. Conductive portions 23. 24 are connected to a source of current or to monitoring devices. The body portion 26 is formed of a flexible non conductive material such as plastic. silastic. or a high medical grade durameter rubber. A rod of transitional ternperature activated mechanical memory material incorporated into shaft portion 21 is shown in phantom in FIGS. Zn and 2h. FIG 2a shows the rod in a typical shape for ease of insertion and advancement of the electrode into the proper body location. \vhile FIG. 2b shows the rod in a shape for effective anchoring of the electrode into a body organ. Effective anchoring is de sirable in the case ofa cardiac electrode to insure positive electrode contact with the endocardium.

FIGS. 3a and 3!) show an example of an atrialvcn tricular pacing electrode having transitional temperature activated mechanical memory material rods 25 and 25' incorporated in both the shaft portion 2| and the tip portion 22 of the electrode. The electrode has two sets of conductive portion. 23. 2-4 and 23'. 24'. FIG. 3!) shows the electrode in a typical proper anchon ing configuration. \\hile FIG. 3a show the rods in typical reformed shapes for ease of insertion of the electrode into a desired portion of a body.

FIGS. 4a and 4h shoyv alternative embodiments ofthe location of the rod 25 in the electrode body 26. Conductors 27. 28 are leads from electrodes 23. 24 to a source of current such as an implantable or external cardiac stimulus generator (pacemaker). or to monitoring diagnostic or sensing devices such as EKG. HIS bundle recorders. oscilliscopes. etc. In FIG. 4a the rod 25 is incorporated in electrode body 26 spaced from the conductors 27. 28. while in FIG. 4b the conductors 27. 28 are hollow, and the rod (or rods] is incorporated within the hollow of one of the conductors (or both of 5 them).

It is obvious that many modifications of the present invention are possible. For instance. the transitional temperature activated mechanical memory material may be constructed in forms other than a rod. The transitional temperature activated mechanical memory ma terial may be formed into a braid l6 which could overlay the catheter body. or be incorporated into the wall or solid cross-section by melting or extruding the body (see FIG. Ic) material around the braid. Similarly it could be in the form of a tube surrounding the outside diameter of the catheter. or a tube incorporated within the catheter body. or a helical wrap around the outside diameter or incorporated within the catheter body. The transitional material may also comprise a whole portion of the catheter or like device. or may extend throughout the whole length or any portion thereof. The conductors themselves. or some part thereof. could be formed from the transitional material.

The possible methods utilizable to heat the transitional temperature activated mechanical memory material to its transitional temperature after proper insertion and advancement are numerous. In addition to merely utilizing body heat. heating could be accomplished by electrical induction heating or liquid immerson or injection. For electrical induction heating. an electrical current from a specially designed current generator is fed to the transitional material. Injection into the catheter or immersion of the transitional material in a heated or cryogenically cooled liquid to either heat up the material above its transitional temperature. or to cool the material below its transitional tempera ture and after proper location discontinue cooling thereby allovving body heat to heat it above its transitional temperature. are also contemplated.

Other transitional temperature activated mechanical memory materials could be utilized besides the above mentioned titanium-nickel and titanium-nickel-cobalt alloys. The above-mentioned alloys are especially advantageous. hovvever. since the anneal. reform. and re vision state cycle may be repeated indefinitely as long as the original annealed temperature is not exceeded. and since in returning to its original shape it is capable of exerting considerable force [recovery stresses of l ltLtltltl psi have been measured on an (1.020 inch diameter wire as it attempted to return to its remembered state I.

Although preferred embodiments. uses. and modifications of the invention have been depicted and dis closed. such description is to be considered illustrative rather than limiting. for the invention may be variously modified. and is to be limited in scope only by construction of the following claims.

What is claimed is:

l. A catheter comprising a. an elongated generally cylindrical body member having a proximate and a distal end. said distal end for insertion into a body. h. a distal portion of said body member capable ofassuming a shape for ready insertion into a body, and a different shape for proper location in a body. and

c. means for shifting said distal portion from said readily insertable shape to said different properly locating shape upon bringing said portion to a specified temperature. said means comprising at least a portion of transitional temperature activated n1echanical memory material formed into said distal portion.

2. A catheter as recited in claim I wherein said body member is formed of flexible non-conductive material having at least one section of conductive material formed on the exterior of a distal portion thereof and an interior section of conductive material leading from said exterior conductive material section to the proximate end ol said body member. whereby the catheter functions as an electrodecatheter.

3. A catheter as recited in claim 2 wherein said interior of conductive material is hollow. and wherein said portion of transitional temperature activated mechanical memory material comprises a rod encompassed by said section of hollow conductive material.

4. A catheter as recited in claim 2 wherein said interior section of conductive material comprises in part said transitional temperature activated mechanical memory material.

5. A catheter as recited in claim 1 wherein said body member is formed of flexible non-conductive material and has an internal cavity extending substantially throughout the length thereof. and at least one passage formed in the distal end oi'the body member communi eating from the exterior thereof to said internal cavity.

6. A catheter as recited in claim 5 wherein said portion of transitional temperature activated mechanical memory material is in the form of a braid in engagement with the distal portion of said body member.

7. A catheter as recited in claim 5 wherein said portion of transitional temperature activated mechanical memory material is in the form of a rod.

8. A catheter as recited in claim I wherein said shape for ready insertion is a straight shape. and wherein said shape for proper location is a curved shape.

9. A catheter as recited in claim I wherein said transitional temperature activated mechanical memory material is an alloy consisting essentially of from 52-56% nickel by weight and correspondingly from about 6 48-44% titanium by weight.

It]. A catheter as recited in claim 1 wherein said transitional temperatureactivated mechanical memory material is an alloy having the formula TiNi Co wherein Ti denotes titanium and constitutes approximately 50 atomic percent of the composition and the term Ni Co denotes nickel and cobalt respectively and make up the remaining approximately 50 atomic percent of the composition. and .r is a factor which varies from greater than 0 to less than I whereby the relative percentage of nickel and cobalt varies inversely from less than IOU percent to more than 0 percent with respect to each other on an atom for atom exchange basis.

I]. The method of properly locating a catheter in a body structure within a body comprising the steps of a. forming a member oftransitional temperature activated mechanical memory material into a first shape.

b. incorporating said member into a portion of a catheter.

c. forming said catheter portion into a second shape for ease of insertion into the body and advancement of said catheter to the body structure.

d. inserting the catheter into the body and advancing said catheter to the body structure.

e. heating said catheter portion to a specified temper ature whereby said catheter portion will revert to said first shape and will thereby assume a shape for proper location of the catheter within the body structurev 12. The method of claim 11 comprising the further step of immersing said portion of the catheter into a cooling fluid until the catheter has been inserted into the body and advanced to the body structure.

13. The method of claim 11 wherein said heating is accomplished by passing an electrical current through said transitional temperature activated mechanical memory material member of the catheter.

14. The method of claim ll wherein said heating is accomplished by immersing said portion ofthe catheter into a heating fluid.

15. The method as recited in claim It wherein said specified temperature is body temperature or slightly less than body temperature. and wherein the body accomplishes said heating. 

1. A catheter comprising a. an elongated generally cylindrical body member having a proximate and a distal end, said distal end for insertion into a body, b. a distal portion of said body member capable of assuming a shape for ready insertion into a body, and a different shape for proper location in a body, and c. means for shifting said distal portion from said readily insertable shape to said different properly locating shape upon bringing said portion to a specified temperature, said means comprising at least a portion of transitional temperature activated mechanical memory material formed into said distal portion.
 2. A catheter as recited in claim 1 wherein said body member is formed of flexible non-conductive material having at least one section of conductive material formed on the exterior of a distal portion thereof and an interior section of conductive material leading from said exterior conductive material section to the proximate end of said body member, whereby the catheter functions as an electrodecatheter.
 3. A catheter as recited in claim 2 wherein said interior of conductive material is hollow, and wherein said portion of transitional temperature activated mechanical memory material comprises a rod encompassed by said section of hollow conductive material.
 4. A catheter as recited in claim 2 wherein said interior section of conductive material comprises in part said transitional temperature activated mechanical memory material.
 5. A catheter as recited in claim 1 wherein said body member is formed of flexible non-conductive material and has an internal cavity extending substantially throughout the length thereof, and at least one passage formed in the distal end of the body member communicating from the exterior thereof to said internal cavity.
 6. A catheter as recited in claim 5 wherein said portion of transitional temperature activated mechanical memory material is in the form of a braid in engagement with the distal portion of said body member.
 7. A catheter as recited in claim 5 wherein said portion of transitional temperature activated mechanical memory material is in the form of a rod.
 8. A catheter as recited in claim 1 wherein said shape for ready insertion is a straight shape, and wherein said shape for proper location is a curved shape.
 9. A catheter as recited in claim 1 wherein said transitional temperature activated mechanical memory material is an alloy consisting essentially of from 52-56% nickel by weight and correspondingly from about 48-44% titanium by weight.
 10. A catheter as recited in claim 1 wherein said transitional temperature activated mechanical memory material is an alloy having the formula TiNixCo1-x wherein Ti denotes titanium and constitutes approximately 50 atomic percent of the composition and the term NixCo1-x denotes nickel and cobalt respectively and make up the remaining approximately 50 atomic percent of the composition, and x is a factor which varies from greater than 0 to less than 1 whereby the relative percentage of nickel and cobalt varies inversely from less than 100 percent to more than 0 percent with respect to each other on an atom for atom exchange basis.
 11. The method of properly locating a catheter in a body structure within a body comprising the steps of a. forming a member of transitional temperature activated mechanical memory material into a first shape, b. incorporating said member into a portion of a catheter, c. forming said catheter portion into a second shape for ease of insertion into the body and advancement of said catheter to the body structure, d. inserting the catheter into the body and advancing said catheter to the body structure, e. heating said catheter portion to a specified temperature whereby said catheter portion will revert to said first shape and will thereby assume a shape for proper location of the catheter within the body structure.
 12. The method of claim 11 comprising the further step of immersing said portion of the catheter into a cooling fluid until the catheter has been inserted into the body and advanced to the body structure.
 13. The method of claim 11 wherein said heating is accomplished by passing an electrical curreNt through said transitional temperature activated mechanical memory material member of the catheter.
 14. The method of claim 11 wherein said heating is accomplished by immersing said portion of the catheter into a heating fluid.
 15. The method as recited in claim 11 wherein said specified temperature is body temperature or slightly less than body temperature, and wherein the body accomplishes said heating. 